BDE 5 and LANGUAGE DRIVERS - BIG PERFORMANCE SLOWDOWN ON QUERIES

PROBLEM DESCRIPTION

Running queries with BDE 5 on local Paradox tables with string fields is much slower than it was with BDE 4.x.
The problem arises under following conditions:

• table is created using international language driver (different than ascii ansi)
• there is at least one string field in the table
• those string fields are included in SQL query

In other words:

• When table is CREATED with DBWINUS0 language driver ('ascii' ansi), the query performance is acceptable.
• When table is CREATED with other language driver (I've used Paradox ANSI Slovene), the query performance goes significantly down.

Under BDE 4.x there is no noticeable performance slowdown!

REPRODUCING THE PROBLEM

Here are the steps to reproduce the problem:

1. In your BDE Administrator set Paradox language driver to ascii ansi (DBWINUS0).
2. Create a local Paradox table (myTable.db) with the following structure:
FIELD1 A 2
FIELD2 A 2
FIELD3 N

Note: the table will be created using ascii ansi Paradox language driver.
3. Populate the table with 90000 records. Fill the field values with random values.
4. Execute SQL query on this table:
SELECT FIELD1, FIELD2, SUM(FIELD3)
FROM myTable
GROUP BY FIELD1, FIELD2

Note: The query itself needs about 3 seconds to complete.
5. Close the program
6. The next step is very important: use BDE Administrator again. This time set Paradox language driver to Paradox ANSI Slovene (ansislov).
7. repeat steps 2 - 5
   
   Note: this time, the table will be created using Paradox ANSI Slovene language driver.
   
   Note: Now the query will need 20 times more than previous query to complete (in my case, about 60 seconds).